Cocaine dependence remains a significant health problem for which effective pharmacotherapy treatments are lacking. In this application for a K23 Mentored Patient Oriented Research Career Development Award, Dr. Elias Dakwar proposes a comprehensive plan towards becoming an independent researcher of innovative treatments for drug dependence. Specifically, this proposal will focus on treating cocaine dependence with sub-anesthetic infusions of ketamine, a high-affinity non-competitive N- methyl-D-aspartate receptor (NMDAR) antagonist, which has recently emerged as a novel antidepressant strategy. Purported mechanisms of its antidepressant action - modulation of the anterior cingulated cortex (ACC), increased neural plasticity in the prefrontal regions of the brain - suggest that ketamine may have a role in the treatment of cocaine dependence as well. Prefrontal dysfunction is believed to be highly associated with the development and maintenance of drug dependence, and ACC dysfunction in particular has been implicated in arousal, impulsivity, and stress sensitivity, as well as in cue reactivity and increased risk of relapse in cocaine users. Disruptions in the glutamate system are hypothesized to underlie these clinically significant impairments in prefrontal functioning, and NMDAR antagonism, via modulation of glutamate, has been proposed as a way to address these deficits. However, the only specific antagonist studied, memantine, failed to show an effect in humans. As recent studies demonstrate, the robust, unique and sustained activity of sub-anesthetic dose ketamine on human brain systems suggest that it may be able to restore normal brain function in a way not observed with memantine, and potentially produce the effects on cocaine dependence that preclinical and animal studies with NMDAR antagonists have been predicting. This trial therefore aims to investigate in a randomized, placebo-controlled trial the effect of ketamine on risk of relapse (time to first cocaine use) in newly abstinent cocaine dependent individuals, as well as to investigate mechanisms of action in regards to stress sensitivity, mindfulness, and impulsivity. Even in the absence of positive findings, the proposed project stands to advance the field by elucidating the role of NMDAR blockade as a treatment strategy for drug dependence. Also, it can contribute more generally to understanding how targeting certain vulnerabilities, such as stress sensitivity and mindfulness impairment, might impact addiction. While pursuing this line of research with the expertise of his mentor (Dr. Frances R. Levin) and preceptors (Drs. Carl Hart and Sanjay Mathew), Dr. Dakwar will concurrently engage in an individualized training program so as to develop in the following important areas: 1) human laboratory and clinical trial study design, methodology, and logistics, 2) advanced biostatistics, 3) responsible conduct of research, 4) manuscript preparation, 5) grant-writing and grant-management skills, and 6) behavioral and translational neurobiology. Overall, this award will ensure Dr. Dakwar's successful transition to an independent investigator of innovative treatments for drug dependence.